1. Field of the Invention
The present invention relates to an outer suspension type lens shielding mask for a projection apparatus, and more particularly to a lens shielding mask mounted outside of a projection lens and designed for matching all kinds of aspect ratios of projection pictures to reduce the leaking of the diffusion light outside of the picture.
2. Description of Related Art
Diffusion light is yielded in a general projector when light is experienced a several reflection and projection after it is emitted from an optical engine. And, a contrast is lowered after the diffusion light is leaked out through the projection lens so that the quality of a dark scene is influenced when the projector is used on such as a home video picture playing.
Therefore, for lowering the darkness of the dark scenes of a motion picture in a projector to enhance the performance of contrast, an optical grating is always added in an optical engine system. But, not only needs it to add elements in entire optical engine or change a design but also helps it nothing for a currently existed projector model if the optical grating is added in the optical engine. Therefore, substantially, it is necessary to add an optical grating device without changing the internal structure of a current projector and increasing production cost.